Technologies are being developed for capturing carbon dioxide (CO2) from industrial gas streams to reduce energy costs and the environmental impact of CO2 in the atmosphere. Major sources of CO2 output include power plants, cement kilns, natural gas processing facilities, ammonia plants, and hydrogen plants. The captured CO2 may have multiple uses, including sequestration, enhanced oil recovery, or accelerated algae growth. In the cases of hydrogen, ammonia, and natural gas, removal of CO2 is necessary to increase the value of the gas stream.
Currently several alternate CO2 capture technologies are in various stages of commercial practice and development. These include chemical absorption with amines (particularly monoethanolamine—MEA), physical adsorption, membrane separation, and cryogenic distillation. In addition, technologies such as oxycombustion and Integrated Gasification Combined Cycle, which remove the carbon or non-oxygen gas components prior to combustion, are being considered as ways to eliminate flue gas removal. Chemical absorption with amines is currently the lowest cost method of CO2 removal for the majority of gas streams, particularly for the clean-up of low levels of CO2 in natural gas. MEA systems are more reactive, and therefore preferred, but the energy load to remove the absorbed CO2 from the MEA, at about 4 million BTU/tonne of CO2 is very high and can require up to about one-third of a power plant's boiler output.